Total system for contrast delivery

ABSTRACT

An apparatus and method enabling the injection of fluid media into a plurality of patients in which is provided a fluid supply source providing multiple doses, metering means for measuring the doses, pressurizing means to effect injection, contamination preventing means between fluid source and patient and, when desired, electronic control means to integrate operation of the apparatus and process.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of application Ser. No. 09/266,727, filedon Mar. 12, 1999, which is a continuation of application Ser. No.08/919,742, filed on Aug. 28, 1997, now U.S. Pat. No. 5,885,216, whichis a division of application Ser. No. 08/534,081, filed on Sep. 22,1995, now U.S. Pat. No. 5,806,519, which is a continuation ofapplication Ser. No. 08/144,462, filed on Oct. 28, 1993, abandoned, thecontents of which are incorporated herein in their entireties.

BACKGROUND OF THE INVENTION

[0002] Contrast media are used in many medical diagnostic andtherapeutic imaging procedures. Diagnostically these include X-rayprocedures for instance, angiography, venography and urography, CTscanning, magnetic resonance imaging (MRI), and ultrasonic imaging.Contrast media is used during therapeutic procedures such asangioplastic and other interventional radiologic procedures. Becausethis contrast material is injected into the patient, it must be sterileand contain a minimum of pyrogens.

[0003] Presently, most contrast is provided in sterilized glass bottles,ranging in size from 20 ml to 200 ml. Plastic packages are alsoavailable. Non-ionic X-ray contrast media is expensive, on the order of$1/ml. Ionic contrast media costs about $0.10/ml. Non-ion contrast hasfewer complications but because of the cost, it is not universally used.MRI contrast costs about $5/ml. All the containers are single use, whichmeans that once a bottle is opened, it should be used for that patientor thrown away, although a multi-use 1,000 ml bottle has been recentlyapproved by the FDA.

[0004] A hospital must purchase and stock many concentrations inmultiple bottle sizes to provide the right amount of the rightconcentration for a specific procedure, while minimizing the wastage ofcontrast remaining in any opened bottles.

[0005] This multitude of sizes and concentrations increases coststhroughout the contrast supplier chain. Manufacturers need to make manybatches with various concentrations, and package each in many sizedbottles. They must have inventories of each on hand to quickly meet thecustomer's request. Each concentration and size entails an addedregulatory burden.

[0006] In the hospital, there are additional costs due to the workpurchasing the various brands and sizes, storage space is required forstocking, cabinets are required in each procedure room; and time isrequired to make sure the right numbers of each bottle are kept in eachroom. Frustration, waste and/or less than optimal studies can occur ifthis complex logistics chain fails at any point.

[0007] To illustrate the problem, consider a manufacturer who makes 5concentrations of contrast, packages them in bottles of 10, 25, 50, 75,100, 150 and 200 ml. The manufacturer now has 35 different products toget approval for, schedule production for, maintain sufficient stock of,and finally, ship to his customers.

[0008] Presently, most hospitals utilize a standard protocol for a givenset of indications. For instance, for a CT scan of the liver, theprotocol may call for 130 ml of contrast injected at 3 ml/s. Thisprotocol is used for a wide variety of patient weights and physicalconditions. One goal of this standardization is to minimize errors.Another is to decrease the likelihood of having to repeat the procedure,with the problem of additional radiation and contrast dose to thepatient.

[0009] However, there are costs associated with this method. Manypatients may get more contrast than they need for an image to bediagnostic. Overdosing wastes contrast, but there is no way with thepresent contrast supply and delivery system to remedy this, withoutstocking many more sizes of bottles and working harder to fill syringes.Other patients may have studies that are less than optimum. They do notreceive enough contrast. The contrast that isn't used doesn't costanything, but there is a much greater chance of having to repeat thewhole procedure, with a much greater cost than a few milliliters ofcontrast. Again, using many bottle sizes and a cumbersome fillingprocedure is the only solution presently available.

[0010] In angiography, there are no set protocols to the same extent asin CT, because patient size determines vessel size which in turndetermines the volume and flow rate needed. This means that a fixedamount of contrast cannot be prepared ahead of time with any confidencethat more won't be needed during the procedure or that a significantamount won't remain and be wasted at the end of the procedure. To avoiddelays while working on the patient, the technician loads more than theaverage amount used, with the realization that some is likely to bewasted, and there still is a chance that a delay will occur when morehas to be loaded.

[0011] Another problem this system addresses is the volume and cost ofitems which must be disposed of after each patient. To save contrast,several small glass bottles may be opened per patient. One or moreplastic syringes, and various tubing arrangements are used. There is acost to purchase and a cost to dispose of each of these items.

[0012] The problems arising from the use of a multiplicity ofconcentrations and container sizes was addressed in German DE 4121568A1.In this disclosure, there is provided a supply tank of contrast agentthat could contain from about 0.1 to as much as 100 liters. The devicealso included a similar tank that contained a diluent so that thecomposition of the resulting mixture could be varied to form a varietyof concentrations. The abstract in the German patent utilizes a bulkmechanical mixer with sequential flow and so it would not seem toprovide for the production of continuously variable concentrations. Nor,and importantly, is there any description of means to preventcross-contamination when the apparatus is used on a plurality ofpatients.

[0013] Machines for mixing IV solutions also do not connect directly tothe patient. Generally, the controls require that the operator knowwhich fluid is in which position and that he choose the mixing ratios.In U.S. Pat. No. 4,341,153, medication is diluted and delivered to asyringe. There are no means described for connection to a patient, thereis no mixing means and only sequential flows are described.

[0014] U.S. Pat. No. 4,610,790 describes in great detail how to makesterile water for diluting medications. Making diluted fluids ismentioned in little detail. U.S. Pat. No. 4,783,273 describes the use ofsterilizing filters to assure the sterility of bulk fluids.Concentration monitors are also described. A serious drawback is the useof chemical sterilants.

[0015] In none of the references mentioned above is a mechanismdescribed which can be used to sequentially or simultaneously injectcontrast into several patients while minimizing the chance ofcross-contamination. Nor is there any mention of information integrityor information transfer so that the proper procedures are followed withthe diluted medications.

OBJECTS OF THE INVENTION

[0016] It is a principal object of this invention to provide an improvedapparatus for injecting a contrast medium sequentially into a pluralityof patients while minimizing the chance of cross-contamination.

[0017] It is another object of this invention to provide a contrastmedium apparatus in which the degree of concentration of the contrastmedium can be continuously varied.

[0018] It is another object of this invention to provide an apparatusfor producing contrast medium in which the medium can either be injecteddirectly into the patient or can be loaded into containers and theninjected by means of an injecting apparatus.

[0019] Other objects and advantages of this invention will be, in part,obvious and, in part, explained by reference to the accompanyingspecification and the drawings in which:

DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 diagrammatically shows an apparatus and a system for makingconstant changes in contrast solution strength and for injecting thefluid or the medium directly into the patient while minimizing thechance of patient-to-patient cross-contamination;

[0021]FIG. 2 is an illustration similar to FIG. 1 showing one method forfilling dose containers and subsequently, putting the dose containers inan injector head for use with a patient.

DESCRIPTION OF THE INVENTION

[0022] It is a goal of this invention to enable delivery of only theamount of contrast needed to a patient, with minimal contrast waste. Acompanion goal is to be able to deliver whatever volume of contrast isneeded, when it is needed, without the arbitrary limitation of syringeor mixing chamber size. The bulk containers can hold more fluid thanwould be given to one patient, so its size is not a limit.

[0023] This is accomplished by changing the way contrast is packaged anddelivered to the patient. Bulk contrast bottles would be manufacturedand distributed to the hospital in only a few number of sizes. A givenprocedure room would only stock one size of bottle. The bulk contrastcould only be available in a single high concentration, the highest usedin current procedures, or it may be available in a limited number ofdifferent concentrations. Two bottle sizes times two concentrations isonly four variations that a manufacturer would potentially have to dealwith.

[0024] It is possible to eliminate the multiplicity of concentrations byproviding bulk diluent and having a contrast delivery system able todilute the most concentrated contrast to any concentration which thedoctor desires. The diluent may be sterile water if the contrast ishyperosmolar, it may be saline if the contrast is iso-osmolar, or it maybe a contrast specific diluent which preserves specific desirableproperties of the contrast during dilution, such as pH. It may be mostconvenient if contrast and diluent are available as a pair from themanufacturer. Diluent is so inexpensive that its waste is not a problem.It is essential that sterility is preserved and that all materials becompatible with the contrast material in use. Pharmaceutical companiesare experienced and have developed considerable expertise in materialsselection.

[0025] In the present disclosure, all embodiments employ an electroniccontrol system which provides the proper fluid flows according to theinstructions of the operator. The operator can either input informationon the concentrations in the various containers, or the control systemcan read a bar code or other code on the bulk container which informs itof the volume and concentration in that bulk container. Also, there canbe sensors which inform the control system when a bulk containerempties, or the control system can keep track of the volume removed andanticipate when it will run out. Anticipation is preferred because anoperator can then be informed during programming of the need to addfluid, rather than start a procedure and then run out.

[0026] There is a benefit to having back-up monitors for these importantparameters. If the system anticipates when fluid runs out, there canstill be fluid assurance sensors, in case a technician installs apartially used bottle. Especially when the contrast is being deliveredto a patient, there needs to be a fluid assurance sensor to prevent theproblem of air embolism. While concentration is not as critical, animproper concentration can necessitate repeat procedure. A sensormeasuring electro-conductivity could be used for both concentrationmonitoring and fluid assurance. There are commercially availableultrasonic sensors designed to detect the presence or absence of fluidin a line. For example, U.S. Pat. No. 4,981,467 discloses such adetector.

[0027] In the present instance, there are two classes of embodiments,the first being those that are directly connected to the patient andsecondly, those which fill a dose container which is then moved to aninjector for delivery to a patient. The first of these embodiments isshown in FIG. 1 where numeral 10 indicates a source of contrast mediumwhich is in the form of a bulk container. Numeral 11 represents asimilar container that is used to hold a supply of diluent, in the eventthat it is desired to reduce the concentration of the contrast mediumcontained within source 10. The containers may be rigid or flexibleglass or a fluid compatible plastic such as polypropylene. If thecontainers are rigid, one of many known methods is used to vent thecontainer with sterile air. A non-vented collapsible container ispreferred to avoid air entry. A metering pump 12 draws contrast from thecontrast supply source 10 at the proper flow rate. A second meteringpump 13 draws diluent (when desired) from the bulk reservoir 11 withinwhich the supply of diluent is contained. A preferred metering pump is aprecision peristaltic pump with santoprene tubing. A wall design similarto that of U.S. Pat. No. 5,230,614 would minimize the pulsatite flowcharacteristics. As the fluids are removed from the containers 10 and11, they are heated by means of the heaters 14 and 15 so that theyapproximate body temperature. The heating, of course, decreases theviscosity of the contrast and makes the fluid more comfortable for thepatient. (Rather than in-line heaters, the bulk containers could beheated.)

[0028] Upon leaving the metering pumps 12 and 13, the fluids meet asthey are joined and flow through a static mixer 20 that contains helicalvanes. The company ConProTec makes many sizes and lengths, some withpolypropylene vanes and a case. These static mixers are designed formixing fluids with very different viscosities and varying dilutionratios. The exact length and diameter to be used will depend to somedegree upon the viscosity of the contrast, dilution ranges, and flowrates. The flow is next through a concentration monitor 23. Withmetering pumps, this is optional but serves a useful verificationfunction signaling if an incorrect mix occurs. Or, the metering pumpscould be replaced by valves and the concentration monitor couldcontinuously monitor and be part of the feed back control of the valves.The monitor measures a property which changes with concentration, suchas electrical conducting, optical refraction index, rotation ofpolarized light, attenuation of sound, speed of sound, density,viscosity, or pressure drop through a fixed section. The mixture nextflows through a back-flow prevention valve 21 which can be either aspring-loaded ball valve or a duck bill valve. This is an importantfeature of the overall device since it helps prevent cross-contaminationwhen the device is used on another patient. By including valve 21 in thesystem, it is possible for fluid to flow only in one direction and thereis no chance that contaminated fluid can be drawn back into the bulkfluid reservoirs from the patient's body.

[0029] Next, the fluid flows through a fluid assurance detector 22 whichmay be an ultrasonic detector so that the presence or absence of air inthe fluid can be determined. Since these types of devices cannot detectsmall air bubbles, by being located before the pressurization pump 25,bubbles will be as large as possible. The fluid assurance detector helpsminimize the chance that a broken line or human error can inject airinto the patient.

[0030] Up until this point, the flow of the liquid has been atrelatively low pressures. To inject the fluid through the connector tube27 and catheter into the patient, relatively high pressures are needed:300 psi for CT, up to 1200 psi for angiography, and 300 psi for MRI.Ultrasound contrast is presently not stable at high pressures, but itsviscosity is similar to that of water so high pressures are notnecessary. Presently this procedure is done by a powerful syringe pump,but these have the draw back that they can only inject one syringe fullat a time. In the present embodiment, the pressurizing pump is a gearpump, with the housing and gears made from TPX. The parts couldoptionally be polycarbonate or Teflon coated polycarbonate. This givesthe clarity needed to check for bubbles, and the drug compatibility ofTeflon. The shaft of the gear pump is connected to an electric motorwith a spline or other coupling mechanism so that the pump head can beremoved and disposed of when required. Depending upon the fluid pathwhich leads to the gear pump and the turbulence within the pump, enoughmixing could take place that the static vane mixer could be eliminated.Fassbender in U.S. Pat. No. 3,349,713 teaches how a gear pump can bemodified to accomplish the mixing of fluids of different viscosities.Because of the widely varying flow rate, this is not possible for allapplications, but some would benefit by the elimination of the mixingelement and the incorporation of its function into the pump.

[0031] The pressurized fluid flows through a 0.2 micron “sterilizing”filter 26. These filters are becoming a standard way to assure sterilityof the solution. Its purpose here is to prevent migration of anybacteria from the patient into the pump. In cooperation with thebackflow valve, cross-contamination in minimized. The sterile filterprevents bacteria from swimming up stream and the back flow preventerstops passive pathogens from being carried backward through the sterilefilter. The fluid coming out of the pump is sterile. The area of thesterile filter will need to be adjusted to accommodate the flow rates ofthe various procedures while maintaining a reasonable pressure drop. Aflexible connector tube 27, which is preferably sterile, carries thefluid to the patient. These are commercially available, usually made outof PVC. This component is disposed of after each patient so that it doesnot need to have long term compatibility with contrast medium.

[0032] At the patient, there is a three-way stopcock 30 and a handsyringe 31. This part can be used for several things. It can be used toaspirate blood and thus, verify good IV catheter placement in CT. It canbe used to inject other medications. It can also be used to fill a handsyringe which can be removed and used for test injections duringangiography. With one position of the stopcock, the fluid flows straightinto the patient.

[0033] The present apparatus includes an electronic control system (ECS)35 to assure that the needs of the patient are met safely. ECS 35 getsinformation on the contents of the bulk reservoirs 10 and 11. Thepreferred method is to read bar codes indicated by numerals 10′ and 11′respectively. Another way is to quiz the operator to enter the data eachtime a bulk reservoir is changed, and then store that information. Theoperator would read the label on or packaged with the bulk reservoir,and enter the appropriate data. This need only be done when a bulkreservoir is changed.

[0034] With each injection, the operator needs to tell the system whatto do. The data most similar to present practice is: 1) theconcentration desired, 2) the flow rate, and 3) the total volume to bedelivered. Present practice also includes multiple phases with variousconstant flow rates during each phase. This system would allow variouscontrast concentrations during each phase as well.

[0035] However, given the capabilities of this system, a preferred setof information is: 1) the procedure being done, and 2) the patientweight. This way the contrast dose could be optimized for the patient.The algorithm would have been previously provided information onmilligrams of iodine per kilogram of patient for each procedure when thesystem was first installed in the hospital. It could displayconcentration, flow rate and volume for operator verification, if theoperator desired. An electronic interface 36 is shown which can connectto the hospital information system to get information on the patient,such as weight. Then the operator would only have to input the patientnumber. The electronic interface could also be connected to the imagingequipment. It could send or receive information so that, for instance,the operator only needs to program the CT scanner with the number ofslices and the body section, and this would be transmitted to thecontrast delivery system to be used in determining flow rates anddelays. The electronic interface would also be used to let the scannertrigger the contrast delivery system or vice versa, after theappropriate delays. A hard copy printer may be optionally part of theuser interface, receiving data from the ECS. This can print a record ofthe actual injection for insertion into the patient records. The outputmay be alphanumeric or be a graphical representation of the injection.

[0036] The operation of delivering fluid to the patient can be startedby the operator with a start switch on the contrast delivery system, orfrom the console of the scanner. There would need to be an armingprocedure similar to that of present injectors to help assure patientsafety.

[0037] In CT, usually only one injection is given, sometimes with pausesand changes in flow rates. As the end of the injection is reached,contrast can be conserved if the contrast flow is stopped and thediluent flow continued so the “bolus” of diluted contrast is flushed outof the tubing and into the patient. In angiography, several injectionsmay be used. It is necessary to flush only after the last injection,although no harm, except injecting a little extra fluid, occurs if theflush follows each injection.

[0038] Another form of waste is using contrast to prime the fluid pathwhich is disposed of with each patient, especially if the concentrationhas not yet been decided upon. The flush or diluent fluid is muchcheaper than the contrast and of lower viscosity, so it can be used toprime the line and make sure that all air has been removed from the pathto the patient.

[0039] The present invention envisions that the “per patient” disposableportion of the apparatus starts just above the sterile filter 26 andends at the patient This “per patient” connection 26′ may be madefarther upstream, with the result that more of the fluid path isdisposed of. This connection must be broken after one patient and madebefore the next. After the connection to one patient is removed, theconnection for the next patient is quickly installed and sterilized, asby means of ultraviolet illumination. The present practice of makingaseptic connections as discussed in U.S. Pat. No. 5,207,642 involvesinserting a spike through a resilient member. This is common practiceand is acceptable when used on one patient although it does not providethe level of sterility provided by ultraviolet illumination. Theremainder of the connector tube and the patient connection end canremain in the sterile bag, ready for the patient who may come in thenext hour or in the next few days. To further enhance sterility, theremainder of the fluid path connecting containers 10, 11; heaters 14,15; metering pumps 12 and 13, etc., is disposable, in which case the“per patient” connection 26′ would be moved farther upstream, asdescribed above, to the desired position, bearing in mind that thedisposable portion is defined as everything below the connection 26′,inclusive of elements downstream of the connection 26′. For example, ifthe connection 26′ is positioned along the fluid path that connects thecontainers, heaters or metering pumps, everything downstream of theconnection 26′, e.g., pump 25, detector 22 and/or valve 21, would beincluded with the disposable portion. However, it is only recommendedthat the disposable portion be replaced when the bulk contrast containeris replaced. Thus, this system needs no active sterilization mechanismnor any toxic sterilants.

[0040] It is possible for the bulk fluid containers to feed more thanone imaging suite, and thus, more than one patient at the same time.With large enough containers, this would be desireable. Each imagingsuite would have all the components shown in FIGS. 1 or 2, except thatthey would share containers 10 and 11 from which fluid could be drawnsimultaneously. Or, there could be just one central ECS, with a userinterface in each imaging suite.

[0041] It is possible to operate the device without the addition of anydiluent. In this case, the static mixer could be removed since therewill be no change in the concentration of the contrast medium. Thissystem provides several simplifications but does require a departurefrom the normal practice that has existed in hospital practices untilthis time. In operating by this method, the operator would put inpatient weight and the procedure, the electronic control system wouldcalculate total volume and flow rate and the patient weight andprocedure would determine the milligrams of Iodine per second that wereneeded. The contrast delivery system would then deliver at the flow rateneeded to provide the proper mgI/s. With the removal of the limitationsof syringe and bottle size, concentration is a redundant parameter whenflow rate can be freely determined.

[0042] In the apparatus shown in FIG. 2, the fluid flows from the staticmixer to a dose container 40. When filled with the proper amount of thedesired concentration, the dose container is separated from the fillingsection and installed in the injecting section 41. This embodiment hastwo benefits. Cross-contamination is more positively prevented becauseair intervenes between the patient and the bulk reservoirs. The sterilefilter may still be used but ideally it and the back flow valve are lesssignificant or optional. Secondly, the system can utilize existingcontrast injectors which hospitals already own, thus, reducing capitalcosts. It is not the preferred embodiment because it imposes limitationsbased upon syringe size.

[0043] The dose container need not be physically moved from one machineto another. It may stay in place, but the connection to the static mixeris opened and the connection to the patient is made. Interlocks wouldassure that a syringe could not be refilled after being connected to apatient. This prevents contamination by pathogens from the patient.

[0044]FIG. 2 shows the filling station and the injector with separateelectronic control systems. To transfer information, a label 42 isprinted and attached to the dose container. This label is read by thecontrast injector and used to set the program. In the event that thelabel is not machine readable then the label can be printed in humanreadable text and the operator could program the contrast injector.

[0045] The embodiment presented above is the one preferred by theinventors, but it is possible for someone skilled in the art torearrange the order of the components in the fluid path and stillaccomplish the goals of this device. In particular, the first componentcould be pressurizing pumps which create high enough pressures to drivethe fluid through the remainder of the system and into the patient. Or,the bulk containers could be pressurized, and the metering pumps couldthen be metering valves. Mixing could be after the sterile filters,right before injection into the patient. These are only a few of thereasonable permutations. It is also a reasonable extension of this ideathat more than two bulk containers may be used. These can sequentiallyor simultaneously dispense their fluid as medically necessary. They maycontain various medicines to be diluted or not. An example isheparinized saline to prevent clotting in the catheter.

[0046] Although the present invention has been described in terms ofpreferred embodiments, the present description is given by way ofexample and is not intended to be limiting to the scope of the inventiondescribed and claimed.

What is claimed is:
 1. A system for producing an image of a patient,comprising: a source of fluid medium; a pressurizing unit operablyassociated with the source of fluid medium for injecting the fluidmedium into the patient; an imaging unit providing an internal image ofthe patient based upon a condition of the fluid medium in the patient;and a control unit adapted to adjust the condition of the fluid mediuminjected into the patient.
 2. The system of claim 1 wherein the fluidmedium is a contrast medium.
 3. The system of claim 2 wherein thecontrast medium is ultrasound contrast.
 4. The system of claim 1 whereinthe condition of the fluid medium in the patient corresponds to at leastone parameter selected from the group of concentration, flow rate andvolume.
 5. The system of claim 1 wherein the condition of the fluidmedium is concentration.
 6. The system of claim 1 wherein thepressurizing unit is adapted to inject at least one bolus of the fluidmedium into the patient.
 7. The system of claim 1, further comprising anelectronic interface in communication with at least one of thepressurizing unit and the imaging unit.
 8. The system of claim 7,further comprising a hospital information system operably associatedwith the electronic interface.
 9. The system of claim 1, furthercomprising a concentration measurement device operable to measure theconcentration of the fluid medium
 10. The system of claim 1, furthercomprising a source of diluent operably associated with the pressurizingunit.
 11. The system of claim 1 wherein the pressurizing unit comprisesa pump.
 12. The system of claim 10, further comprising a mixer formixing the fluid medium and the diluent.
 13. The system of claim 1,further comprising a fluid path disposed between the pressurizing unitand the patient.
 14. The system of claim 13, further comprising a filterdisposed in the fluid path.
 15. The system of claim 13, furthercomprising a back-flow valve disposed in the fluid path.
 16. The systemof claim 13, further comprising a fluid assurance detector in the fluidpath.
 17. A method for controlling an imaging procedure, comprising:pressurizing a fluid medium for injection into the patient; generatingan internal image of the patient based upon a condition of the fluidmedium injected into the patient; and adjusting the condition of thefluid medium injected into the patient.
 18. The method of claim 17wherein the condition is concentration.
 19. The method of claim 17 wherein the fluid medium comprises ultrasound contrast.
 20. A system forproducing an image of a patient, comprising: a source of contrastmedium; a pressurizing unit operably associated with the source ofcontrast medium for injecting the contrast medium into the patient; animaging unit providing an internal image of the patient based upon acondition of the contrast medium in the patient; a control unit adaptedto adjust the condition of the contrast medium injected into thepatient; an electronic interface in communication with at least one ofthe pressurizing unit and the imaging unit; and a fluid path disposedbetween the pressurizing unit and the patient.